WO2001018537A2 - Process for determining the acidity of a washing solution for fibres - Google Patents
Process for determining the acidity of a washing solution for fibres Download PDFInfo
- Publication number
- WO2001018537A2 WO2001018537A2 PCT/EP2000/008845 EP0008845W WO0118537A2 WO 2001018537 A2 WO2001018537 A2 WO 2001018537A2 EP 0008845 W EP0008845 W EP 0008845W WO 0118537 A2 WO0118537 A2 WO 0118537A2
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- Prior art keywords
- measurement
- acidity
- washing solution
- fibres
- ultrasonic sound
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/18—Water
- G01N33/1813—Specific cations in water, e.g. heavy metals
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02809—Concentration of a compound, e.g. measured by a surface mass change
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02863—Electric or magnetic parameters
Definitions
- the invention pertains to a process for determining the acidity of a washing solution for removing adhering acid or base from a fibre.
- the most widely used fibre-forming processes are melt spinning and solution spinning. In both processes, the polymer is extruded through the orifices of a spinneret. In melt spinning molten polymer is used, while in solution spinning use is made of a spinning dope solution comprising a dispersed or dissolved polymer. After the extrusion of the molten polymer or the spinning dope solution, different spinning techniques can be applied to produce the fibres.
- Spinning dope solutions can be acidic.
- a polymer comprising poly(p-phenylene terephthalamide) is usually dispersed in a sulfuric acid solution for the production of aramid fibres.
- traces of the acidic solution often adhere to the produced fibres. These traces need to be removed in order to prevent hydrolytic degradation of the fibres, which occurs especially above 20°C.
- a washing solution is used to remove adhering acids or bases from a fibre. It is important to measure and adjust the acidity of the washing solution in such a way that fibres with a minimum amount of adhering acid or base can be produced.
- the acidity can be measured directly by using a titration method or a pH measurement.
- pH measurements are not preferred for accurate determination of the acidity because there is a necessity to calibrate the pH electrode very often and because the inaccuracy of the measurement increases as the pH-value deviates further from pH 6 to 8.
- the acidity of the washing solution is measured using a titration method, as described in M. Valcarcel et al., Techniques and Instrumentation in Analytical Chemistry, Vol.
- the acidity of a washing solution can also be determined indirectly by using another analytical method such as a density, conductivity, ultrasonic sound or refractive index measurement.
- another analytical method such as a density, conductivity, ultrasonic sound or refractive index measurement.
- the results obtained carrying out one of these measurements in a washing solution are insufficient for accurate determination of the acidity when there are variable concentrations of salts or compounds present in the solution.
- sulfuric acid is used for the preparation of a spinning dope solution for the production of fibres, and traces of the solution still adhere to the produced fibres before washing, then variable concentrations of sodium sulfate will often be present in a washing solution for these fibres after interaction of the sulfuric acid with, for example, caustic soda.
- the principal object of the present invention to provide a method for rapid and accurate determination of the acidity of a washing solution for the production of fibres with a minimum amount of adhering acid or base.
- the method is applicable on-line.
- the device used for the determination preferably requires less maintenance than do the commercially available devices presently employed in the commonly used titration methods.
- a process has been found that permits rapid and accurate determination of the acidity of a washing solution for removing adhering acid or base from a fibre.
- the process is characterized in that the determination is carried out using a combination of at least two different analytical methods, at least one of which is selected from the density, conductivity, ultrasonic sound, and refractive index measurements. Rapid and accurate determination makes it possible to adjust the acidity of a washing solution in such a way that fibres with a minimum amount of adhering acid or base can be produced.
- fibres with a minimum amount of adhering acid or base is meant that the molar ratio of the OH " ions to the H + ions present in the medium adhering to said fibres is about 1 , with the provisio that these ions are not chemically bound to the fibres.
- This ratio can be determined indirectly by analyzing the amount of counter-ions of the OH " and the H + ions in the medium, for example the amount of Na + ions when NaOH is used for washing the fibre and the amount of SO 4 2" ions when the fibre is spun from a sulfuric acid solution.
- a Na/S ratio can be determined by using X-ray diffraction spectroscopy (XRF).
- XRF X-ray diffraction spectroscopy
- any other suitable analytical method may also be used.
- the combination according to the invention comprises at least two analytical methods selected from the density, conductivity, ultrasonic sound and refractive index measurements.
- the analytical devices used for said measurements require less maintenance and are easier to calibrate than the commercially available devices presently employed in the commonly used titration methods. Furthermore, the devices used for these measurements are most practical when it comes to installation for measuring on-line.
- the combination according to the invention comprises a conductivity measurement or a density measurement, because such a combination enables highly accurate determination of the acidity of a washing solution for fibres.
- the combination comprises at least : 1) a conductivity measurement and an ultrasonic sound measurement, 2) a conductivity measurement and a density measurement, or 3) a density measurement and an ultrasonic sound measurement.
- the combination comprises at least a conductivity measurement and an ultrasonic sound measurement, because the devices used for these measurements are easiest to clean and require the least maintenance. This is especially desirable when the measurements are carried out on-line.
- the measurements "are carried out on-line” means that they are carried out continuously or at certain time intervals in a washing solution or any process stream consisting of this solution.
- the measurements are carried out on-line automatically, for example controlled by an electronic and/or computer system.
- said system is able to give signals or commands for correcting the acidity of the washing solution when necessary, thereby enabling the production of a fibre with a minimum amount of adhering acid or base.
- the acidity of a washing solution for fibres can be determined by combining the results obtained by carrying out at least two analytical methods according to the invention.
- calibrations need to be carried out in order to determine the correlation of the results of each method with the acidity of the washing solution.
- Such a calibration is best performed by measuring on representative samples with different concentrations of salts or compounds, which are also present in the washing solution for fibres of which the acidity needs to be determined, the different concentrations in the samples having been chosen according to an experimental design.
- An example of such an experimental design can be found in Table I of Example I.
- a calibration equation for each combination of analytical methods can be calculated from the results obtained by measuring in the samples, using a standard statistical technique, e.g. multiple linear regression or partial least squares, as described in H. Martens et al., Multivariate calibration, John Wiley and Sons, Chichester, 1989, or in D.L. Massart et al., Chemometrics: A Textbook, Elsevier, Amsterdam, 1987.
- the process according to the invention can be used to remove adhering acid or base from any fibre.
- the process can be applied to fibres produced using an acidic spinning dope solution comprising an aromatic polyamide, such as poly(p-phenylene terephthalamide), and sulfuric acid.
- an ultrasonic device comprising an emitter and a receiver for ultrasonic sound.
- the device generates ultrasonic sound waves at the emitter, measures the time it takes before such a wave from the emitter passing through the solution arrives at the receiver, and calculates the propagation velocity as the distance between the emitter and the receiver divided by this time.
- Ultrasonic sound with a frequency of at least 50 kHz can be used for this measurement.
- the propagation velocity (v) of ultrasonic sound in general depends on the density (d) and the adiabatic compressibility (c) of a solution according to the following equation:
- the ultrasonic device used for measuring the propagation velocity of ultrasonic sound comprises a temperature sensor in order to enable a local adjustment of the temperature in the solution between the emitter and receiver.
- the propagation velocity of ultrasonic sound in a washing solution is also slightly dependent on the flow of the solution in which the measurement takes place. Preferably, this propagation velocity is measured perpendicular to the flow direction. If a combination of analytical methods according to the invention comprising at least a conductivity measurement, or a density measurement, or a refractive index measurement is used, then these measurements are carried out according to general conditions and instructions as described in F. McLennan and B. Kowalski., Process Analytical Chemistry, Glasgow, 1995.
- the samples characterized in Table I were prepared by adding the required amount of salt to aqueous solutions.
- the different concentrations of sodium hydroxide (NaOH), sodium sulfate (Na 2 SO 4 ), and sodium carbonate (Na 2 CO 3 ) in the samples were chosen according to a central composite design.
- the samples are representative of the composition of a washing solution for aramid fibres with adhering traces of sulfuric acid.
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The invention pertains to a process for determining the acidity of a washing solution for removing adhering acid or base from a fibre. The determination is carried out by using a combination of at least two different analytical methods, at least one of which is selected from the density, conductivity, ultrasonic sound, and refractive index measurements. The determination makes it possible to adjust the acidity of the washing solution in such a way that fibres with a minimum amount of adhering acid or base can be produced.
Description
Process for determining the acidity of a washing solution for fibres
The invention pertains to a process for determining the acidity of a washing solution for removing adhering acid or base from a fibre.
There are different ways to produce fibres. The most widely used fibre-forming processes are melt spinning and solution spinning. In both processes, the polymer is extruded through the orifices of a spinneret. In melt spinning molten polymer is used, while in solution spinning use is made of a spinning dope solution comprising a dispersed or dissolved polymer. After the extrusion of the molten polymer or the spinning dope solution, different spinning techniques can be applied to produce the fibres.
Spinning dope solutions can be acidic. For example, a polymer comprising poly(p-phenylene terephthalamide) is usually dispersed in a sulfuric acid solution for the production of aramid fibres. After the solution has been extruded and a spinning technique applied, traces of the acidic solution often adhere to the produced fibres. These traces need to be removed in order to prevent hydrolytic degradation of the fibres, which occurs especially above 20°C.
Commonly, a washing solution is used to remove adhering acids or bases from a fibre. It is important to measure and adjust the acidity of the washing solution in such a way that fibres with a minimum amount of adhering acid or base can be produced. The acidity can be measured directly by using a titration method or a pH measurement. However, pH measurements are not preferred for accurate determination of the acidity because there is a necessity to calibrate the pH electrode very often and because the inaccuracy of the measurement increases as the pH-value deviates further from pH 6 to 8. Most commonly, the acidity of the washing solution is measured using a titration method, as described in M. Valcarcel et al., Techniques and Instrumentation in Analytical
Chemistry, Vol. 9, Elsevier, Amsterdam, 1988. However, the information time of said titration method is relatively long. Therefore, it is very difficult or even impossible to adjust the acidity quickly enough to obtain fibres with a minimum amount of adhering acid or base. Another disadvantage of said method is the need to use reagents when carrying out a titration. Furthermore, a titration device used for measuring the acidity of a washing solution on-line requires relatively frequent maintenance.
The acidity of a washing solution can also be determined indirectly by using another analytical method such as a density, conductivity, ultrasonic sound or refractive index measurement. However, the results obtained carrying out one of these measurements in a washing solution are insufficient for accurate determination of the acidity when there are variable concentrations of salts or compounds present in the solution. For example, if sulfuric acid is used for the preparation of a spinning dope solution for the production of fibres, and traces of the solution still adhere to the produced fibres before washing, then variable concentrations of sodium sulfate will often be present in a washing solution for these fibres after interaction of the sulfuric acid with, for example, caustic soda.
It is accordingly the principal object of the present invention to provide a method for rapid and accurate determination of the acidity of a washing solution for the production of fibres with a minimum amount of adhering acid or base. Preferably, the method is applicable on-line. Furthermore, the device used for the determination preferably requires less maintenance than do the commercially available devices presently employed in the commonly used titration methods.
Surprisingly, a process has been found that permits rapid and accurate determination of the acidity of a washing solution for removing adhering acid or base from a fibre. The process is characterized in that the determination is carried out using a combination of at least two different analytical methods, at least one of which is selected from the density, conductivity, ultrasonic sound,
and refractive index measurements. Rapid and accurate determination makes it possible to adjust the acidity of a washing solution in such a way that fibres with a minimum amount of adhering acid or base can be produced.
By fibres with a minimum amount of adhering acid or base is meant that the molar ratio of the OH" ions to the H+ ions present in the medium adhering to said fibres is about 1 , with the provisio that these ions are not chemically bound to the fibres. This ratio can be determined indirectly by analyzing the amount of counter-ions of the OH" and the H+ ions in the medium, for example the amount of Na+ ions when NaOH is used for washing the fibre and the amount of SO4 2" ions when the fibre is spun from a sulfuric acid solution. In this specific example a Na/S ratio can be determined by using X-ray diffraction spectroscopy (XRF). However, any other suitable analytical method may also be used.
Preferably, the combination according to the invention comprises at least two analytical methods selected from the density, conductivity, ultrasonic sound and refractive index measurements. The analytical devices used for said measurements require less maintenance and are easier to calibrate than the commercially available devices presently employed in the commonly used titration methods. Furthermore, the devices used for these measurements are most practical when it comes to installation for measuring on-line. Even more preferably, the combination according to the invention comprises a conductivity measurement or a density measurement, because such a combination enables highly accurate determination of the acidity of a washing solution for fibres. This is especially the case for a process according to the invention wherein the combination comprises at least : 1) a conductivity measurement and an ultrasonic sound measurement, 2) a conductivity measurement and a density measurement, or 3) a density measurement and an ultrasonic sound measurement. Most preferably, the combination comprises at least a conductivity measurement and an ultrasonic sound measurement, because the devices used for these measurements are easiest to clean and require the least maintenance. This is especially desirable when the
measurements are carried out on-line.
The measurements "are carried out on-line" means that they are carried out continuously or at certain time intervals in a washing solution or any process stream consisting of this solution. Preferably, the measurements are carried out on-line automatically, for example controlled by an electronic and/or computer system. Even more preferably, said system is able to give signals or commands for correcting the acidity of the washing solution when necessary, thereby enabling the production of a fibre with a minimum amount of adhering acid or base.
The acidity of a washing solution for fibres can be determined by combining the results obtained by carrying out at least two analytical methods according to the invention. First, calibrations need to be carried out in order to determine the correlation of the results of each method with the acidity of the washing solution. Such a calibration is best performed by measuring on representative samples with different concentrations of salts or compounds, which are also present in the washing solution for fibres of which the acidity needs to be determined, the different concentrations in the samples having been chosen according to an experimental design. An example of such an experimental design can be found in Table I of Example I. A calibration equation for each combination of analytical methods can be calculated from the results obtained by measuring in the samples, using a standard statistical technique, e.g. multiple linear regression or partial least squares, as described in H. Martens et al., Multivariate calibration, John Wiley and Sons, Chichester, 1989, or in D.L. Massart et al., Chemometrics: A Textbook, Elsevier, Amsterdam, 1987.
The process according to the invention can be used to remove adhering acid or base from any fibre. For example, the process can be applied to fibres produced using an acidic spinning dope solution comprising an aromatic polyamide, such as poly(p-phenylene terephthalamide), and sulfuric acid.
If a combination of analytical methods according to the invention comprising at least an ultrasonic sound measurement is used, then the propagation velocity of ultrasonic sound in a washing solution is measured using an ultrasonic device comprising an emitter and a receiver for ultrasonic sound. The device generates ultrasonic sound waves at the emitter, measures the time it takes before such a wave from the emitter passing through the solution arrives at the receiver, and calculates the propagation velocity as the distance between the emitter and the receiver divided by this time. Ultrasonic sound with a frequency of at least 50 kHz can be used for this measurement.
The propagation velocity (v) of ultrasonic sound in general depends on the density (d) and the adiabatic compressibility (c) of a solution according to the following equation:
v = c *d
Consequently, if the density of the solution decreases, then the propagation velocity of ultrasonic sound in the solution increases. The density is dependent, int. al., on the temperature, the pressure, and the concentration of any compound or salt in the solution, such as sodium sulfate, sodium chloride, sodium hydroxide. Therefore, the propagation velocity of ultrasonic sound in a washing solution is not only dependent on the concentration of a compound or salt, but also on the temperature and the pressure in this solution. Preferably, the ultrasonic device used for measuring the propagation velocity of ultrasonic sound comprises a temperature sensor in order to enable a local adjustment of the temperature in the solution between the emitter and receiver.
The propagation velocity of ultrasonic sound in a washing solution is also slightly dependent on the flow of the solution in which the measurement takes place. Preferably, this propagation velocity is measured perpendicular to the flow direction.
If a combination of analytical methods according to the invention comprising at least a conductivity measurement, or a density measurement, or a refractive index measurement is used, then these measurements are carried out according to general conditions and instructions as described in F. McLennan and B. Kowalski., Process Analytical Chemistry, Glasgow, 1995.
The invention will be further illustrated with reference to the following examples.
Example I :
The samples characterized in Table I were prepared by adding the required amount of salt to aqueous solutions. The different concentrations of sodium hydroxide (NaOH), sodium sulfate (Na2SO4), and sodium carbonate (Na2CO3) in the samples were chosen according to a central composite design. The samples are representative of the composition of a washing solution for aramid fibres with adhering traces of sulfuric acid.
TABLE I
Sample NaOH Na2CO3 Na2SO4
(% by weight) (% by weight) (% by weight)
1 0.66 0.070 1.60
2 1.34 0.070 1.60
3 1.01 0.020 1.60
4 1.00 0.120 1.60
5 1.00 0.070 0.09
6 1.00 0.070 3.11
7 0.80 0.041 0.70
8 1.20 0.040 0.71
9 0.80 0.100 0.70
10 1.20 0.100 0.70
1 1 0.80 0.040 2.50
12 1.21 0.040 2.50
13 0.79 0.102 2.51
14 1.19 0.100 2.50
15 1.00 0.072 1.61
Measurements were carried out on the above-mentioned samples using the analytical methods and devices specified below in Table II. The measurements were carried out at ambient pressure and room temperature. The density measurements were corrected to 25°C. The results of the measurements are presented in Table III.
TABLE II
Analytical method Abbreviation Device
Density measurement (d) Kyoto DA 310M
Conductivity measurement (c) Yokogawa ISC40G-PG-T1-
05
(inductive type of measurement)
Ultrasonic sound (v) LiquiSonic 30 (SensoTech) measurement
Refractive Index (ri) Krϋss AR-8 measurement
TABLE III
Sample Conductivity Density Propagation Refractive velocity of Index ultrasonic sound
(mS) (g/ml) (m/s)
1 46.20 1.019385 1519.11 1.3376
2 75.29 1.026820 1535.77 1.3394
3 60.02 1.022725 1526.60 1.3384
4 60.75 1.023645 1528.26 1.3384
5 49.20 1.009595 1509.88 1.3362
6 70.00 1.036765 1544.52 1.3405
7 44.94 1.012645 1511.48 1.3365
8 62.19 1.016990 1521.74 1.3374
9 45.97 1.013190 1512.39 1.3365
10 63.21 1.017640 1522.58 1.3376
11 57.93 1.028780 1532.10 1.3389
12 74.32 1.033185 1542.39 1.3401
13 58.56 1.029385 1533.26 1.3394
14 74.08 1.033675 1543.10 1.3405
15 60.05 1.023195 1527.50 1.3384
The correlation coefficients for the NaOH concentration presented in Table IV were determined from these results for each analytical method according to standard statistical methods.
TABLE IV
Analytical method Correlation coefficient for the NaOH concentration
Conductivity measurement 0.806
Density measurement 0.258
Ultrasonic sound measurement 0.433
Refractive Index measurement 0.367
It was concluded from Table IV that the results for each analytical method as such do not show a good correlation with the sodium hydroxide concentration. Therefore, it is not possible to determine accurately the acidity of a washing solution comprising variable concentrations of compounds or salts when only one of the analytical methods is used.
Example II :
The results of two different analytical methods in Table III were combined in order to determine the correlation of these combined results with the sodium hydroxide concentration.
The predicted error (expressed as the standard deviation of the difference between prediction and reference value) in the NaOH concentration was determined for each combination of analytical methods as presented in Table V, using multivariate mathematical techniques, e.g. partial least squares or multiple linear regression.
TABLE V
It was concluded from Table V that especially the combined results of the following combinations of analytical methods (for abbreviations, see Table II) show a good correlation with the NaOH concentration in this example: (c)+(d), (c)+(v), (c)+(ri), and (d)+(v). The correlation of these combined results with the NaOH concentration is far better than the correlation of the results of just one analytical method with the NaOH concentration, as described in Example I.
Claims
1. A process for determining the acidity of a washing solution for removing adhering acid or base from a fibre, characterized in that the determination is carried out by using a combination of at least two different analytical methods, at least one of which is selected from the density, conductivity, ultrasonic sound, and refractive index measurements.
2. The process according to claim 1 wherein the combination comprises at least two analytical methods selected from the density, conductivity, ultrasonic sound, and refractive index measurements.
3. The process according to claim 1 or 2 wherein the combination comprises an ultrasonic sound measurement.
4. The process according to claim 1 or 2 wherein the combination comprises a conductivity measurement or a density measurement.
5. The process according to claim 3 wherein the combination comprises at least a conductivity measurement and an ultrasonic sound measurement.
6. The process according to claim 1 wherein the combination comprises at least a conductivity measurement and a density measurement.
7. The process according to claim 3 wherein the combination comprises at least a density measurement and an ultrasonic sound measurement.
8. The process according to any one of claims 1 - 7 wherein the measurements are carried out on-line.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0200948A GB2367893B (en) | 1999-09-02 | 2000-08-31 | Process for determining the acidity of a washing solution for fibres |
| JP2001522075A JP2003508787A (en) | 1999-09-02 | 2000-08-31 | How to measure the acidity of a fiber wash |
| US10/070,135 US6606901B1 (en) | 1999-09-02 | 2000-08-31 | Process for determining the acidity of a washing solution for fibers |
| AU74187/00A AU7418700A (en) | 1999-09-02 | 2000-08-31 | Process for determining the acidity of a washing solution for fibres |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP99202845.6 | 1999-09-02 | ||
| EP99202845 | 1999-09-02 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| WO2001018537A2 true WO2001018537A2 (en) | 2001-03-15 |
| WO2001018537A3 WO2001018537A3 (en) | 2001-08-02 |
Family
ID=8240598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP2000/008845 Ceased WO2001018537A2 (en) | 1999-09-02 | 2000-08-31 | Process for determining the acidity of a washing solution for fibres |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US6606901B1 (en) |
| JP (1) | JP2003508787A (en) |
| AU (1) | AU7418700A (en) |
| GB (1) | GB2367893B (en) |
| WO (1) | WO2001018537A2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007012904A3 (en) * | 2005-07-26 | 2007-04-12 | Sandor Lako | Method and apparatus for measuring the elementary composition of wastewaters |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI116730B (en) * | 2003-07-31 | 2006-02-15 | Outokumpu Oy | Method and apparatus for controlling demetallization |
| JP2008203129A (en) * | 2007-02-21 | 2008-09-04 | Kyoto Electron Mfg Co Ltd | Salinity meter |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB950198A (en) | 1960-07-08 | 1964-02-19 | Atomic Energy Authority Uk | A method of testing and apparatus applicable to the control of the manufacture of uranium |
| FR2145795A5 (en) | 1971-07-12 | 1973-02-23 | Schleimer James | Water treatment system |
| US3780577A (en) * | 1972-07-03 | 1973-12-25 | Saratoga Systems | Ultrasonic fluid speed of sound and flow meter apparatus and method |
| SE377348B (en) * | 1972-07-14 | 1975-06-30 | Mo Och Domsjoe Ab | |
| AU596012B2 (en) * | 1987-05-29 | 1990-04-12 | Godfrey Howden Proprietary Limited | Liquid testing apparatus |
| US4996160A (en) | 1987-06-09 | 1991-02-26 | The Dow Chemical Company | Method and apparatus for quantitative measurement of ionic and organic contaminants remaining on cleaned surfaces |
| GB2217848B (en) * | 1988-04-28 | 1991-11-27 | British Nuclear Fuels Plc | Monitoring the chemical composition of a fluid |
| DE19533927A1 (en) | 1995-09-13 | 1997-03-27 | Michael Prof Dr Dr Gitis | On-line measuring of water concn. |
| US5760297A (en) * | 1997-03-24 | 1998-06-02 | Mesa Laboratories, Inc. | System for measuring acid concentration in an alkylation process |
-
2000
- 2000-08-31 AU AU74187/00A patent/AU7418700A/en not_active Abandoned
- 2000-08-31 US US10/070,135 patent/US6606901B1/en not_active Expired - Fee Related
- 2000-08-31 JP JP2001522075A patent/JP2003508787A/en not_active Withdrawn
- 2000-08-31 WO PCT/EP2000/008845 patent/WO2001018537A2/en not_active Ceased
- 2000-08-31 GB GB0200948A patent/GB2367893B/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007012904A3 (en) * | 2005-07-26 | 2007-04-12 | Sandor Lako | Method and apparatus for measuring the elementary composition of wastewaters |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0200948D0 (en) | 2002-03-06 |
| GB2367893B (en) | 2003-11-12 |
| GB2367893A (en) | 2002-04-17 |
| WO2001018537A3 (en) | 2001-08-02 |
| AU7418700A (en) | 2001-04-10 |
| US6606901B1 (en) | 2003-08-19 |
| JP2003508787A (en) | 2003-03-04 |
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